Clutch flywheel

ABSTRACT

A bimetal flywheel for clutches including a steel inner disc and an outer aluminum ring secured together by interlock means, the steel disc including a smooth radial surface for bearing against a disc of a clutch assembly and the outer ring being adapted to carry a cover for the clutch assembly, and the interlock means opposing separation of the inner disc and outer ring as the disc presses against the radial face when the associated clutch is engaged.

United States Patent Capanna 14 1 Jan. 18,1972

CLUTCH FLYWHEEL Anthony Cnpanna, 209 Via Colusa, Palos Verdes Estates,Calif. 90274 Filed: Dec. 31, 1969 Appl. 110.: 889,633

inventor:

US. Cl ..l92/l07 M, 74/572 Int. Cl ..Fl6d 13/60 Field ofSearch..74/572,574; 193/107 M,70.i3

Relerences Cited UNITED STATES PATENTS 10/1919 Sperry ..74/s72 1/1921Emmet... ..74/s72 10/1927 Walker ..74/572 Defosse 1 ..74/572 Schiefer....l92/l07 M Weiland 192/7013 Primary Examiner-Benjamin W. WycheAssistant Examiner-Warren Olsen Attorney-Robert R. Meads [57] ABSTRACT 4Claims, 4 Drawing Figures CLUTCH FLYWHEEL The present invention relatesto improvements in automotive clutches and the like, and, moreparticularly, to a novel flywheel construction particularly useful insuch clutches.

It is particularly important that racing cars have the capability ofrapidly accelerating and decelerating. Accordingly, it is desirable toreduce the mass and hence the inertia of all rotating and reciprocatingparts in and associated with racing cars engines. This is particularlytrue of the flywheels included in the clutch assemblies of racing carshaving manual shift transmissions. This desire has led to thedevelopment of aluminum flywheels. While such flywheels are lightweightand thus able to be rapidly accelerated and decelerated, the clutch padengaging surfaces unfortunately have very poor wear characteristics andthe flywheels tend to warp. In an attempt to counteract such wearproblems, metal plates have been bonded to the radial faces of aluminumflywheels and in other instances the radial faces have been sprayed witha metallic material. Neither of these proposals have proven successful.The metal plates rapidly curl, separate from the flywheel, and produceundesired excessive wear on the associated clutch pads. The spraycoatings rapidly wear off.

It is therefore an object of the present invention to provide a uniqueclutch flywheel which is capable of being rapidly accelerated anddecelerated and yet is so constructed as to resist warpage and toprovide clutch disc engaging surfaces having high, uniform wearcharacteristics.

Another object of the invention is to provide a flywheel of theforegoing character comprising a central disc of a strong, sturdy, wearresistant material surrounded by an outer ring of a lightweight metalwith interlocking means therebetween which prevents separation of theinner disc and outer ring during engagement and disengagement of theclutch.

A further object of the present invention is to provide a flywheel ofthe foregoing character including interlocking means comprising matingannular shoulders on an outer periphery of the inner disc and an innersurface of the outer ring.

The foregoing as well as other objects and advantages of the presentinvention may be more clearly understood by reference to the followingdetailed description when considered with the drawing, which by way ofexample only illustrates a clutch including a flywheel including thefeatures of the present invention.

In the drawing:

FIG. 1 is a sectional side view of an automobile clutch including theflywheel having the features of the present invention;

FIG. 2 is a rear view of the flywheel;

FIG. 3 is a front view of the flywheel; and

FIG. 4 is a fragmentary sectional view of an outer peripheral portion ofthe flywheel illustrating the interlock between the inner central discand the outer ring comprising the flywheel.

FIG. 1 illustrates a clutch assembly for an automobile including oneform of the flywheel 12 of the present invention. But for the structureof the flywheel, the clutch assembly is of conventional design.Therefore, the assembly will be described only briefly and to the extentnecessary to understand the function of the flywheel in a clutchassembly.

As illustrated, the clutch assembly 10 includes an outer housing 13 ofgenerally bell-shaped construction having coaxial and opposing openings14 and 16 for receiving an engine crankshaft 18 and a transmission shaft20, respectively. Within the outer housing 13, the clutch assembly 10includes the flywheel 12, inner cover member 22, clutch disc 24,pressure plate 26, and spring plate 28. Generally speaking, with theclutch engaged, as illustrated, rotational motion of the crankshah I8 istransferred to the transmission shaft 20 by the clutch disc 24 rotatingwith the flywheel 12.

More particularly, the flywheel I2 is generally disc-shaped and isbolted or otherwise secured to the end of the crankshaft 18 within theouter housing. The inner cover member 22 includes an outer radial flange30, an annular portion 32 extending axially from the flange, and agenerally radial flange 34 extending inwardly from a right end of theannular portion. The radial flange 30 is secured by bolts 36 to theright face of the flywheel 12 adjacent its peripheral edge. The springplate 28 is secured by bolts 37 to the inner radial flange 34 within theinner cover member 22 and is adapted for flexing in an axial directionrelative to the crank and transmission shafts. The pressure plate 26 iscoupled to the spring plate 28 by a plurality of retainer springs, oneof which is illustrated at 38, and is coaxially oriented within theinner cover member 22 between the spring plate and the clutch disc 24.The clutch disc 24, in turn, is secured to a female spline 40 and iscaptured between the pressure plate and the right face of the flywheel12.

The clutch assembly 10 as described is coupled to the transmission shaft20 through the female spline 40. In this regard the transmission shaft20 carries a collar 42 including an annular groove 44. The collar isadapted to slide on the transmission shaft 20 up against a throwoutbearing 46 which, in turn, bears against the spring plate 28. The springplate 48 includes a central opening 48 for receiving a male spline $0 onthe end of the transmission shaft. The male spline 50 mates with thefemale spline 40 and carries a coaxial pin 52 on its forward end whichis bearing supported in a cavity 54in the end of the crankshaft 18. Thepin and its associated bearing provide end and centering support for thetransmission shaft 20 within the clutch assembly. Thus arranged,rotation of the clutch disc 24 and female spline 40 with the flywheel 12produces a like rotation of the transmission shaft 20.

Engagement and disengagement of the clutch assembly and hence operationthereof is controlled by an am 56 pivoted at 58 to the right end of theouter housing 13. The end of the arm 56 within the housing includes afinger 60 riding in the annular slot 44 of the collar 42. The outer endof the arm 56 extends beyond the outer housing through a slot 62 forconnection to the clutch pedal within the vehicle associated with theclutch assembly.

As illustrated, the clutch assembly 10 is normally engaged. In such acondition, the flywheel l2 continuously rotates with the crankshaft 18to turn with it the inner cover member 22 and spring plate 28. Thespring plate 28 bears tightly against the pressure plate 26 and urgesthe pressure plate to the left toward the disc 24. The disc, in turn, isurged tightly against the right radial face to the flywheel 12 to causethe disc to rotate with the flywheel. As the disc rotates, it turns in alike manner the female spline 40 to drive the transmission shaft 20through the male spline 50 on the end of the shaft.

When it is desired to disengage the clutch, the clutch pedal isdepressed causing the arm 56 to move to the right as indicated by thearrow 63. This produces a movement of the collar 42 to the left, asindicated by the arrow 64. Movement of the collar 42 to the left forcesthe throwout bearing 46 in a like direction against the inner portion ofthe spring plate 28. This produces a deflection of the outer edge of thespring plate to theright and causes the pressure plate 26 to moveslightly away from the disc 24. This allows the pad to slip relative tothe flywheel l2 and halts the transfer of rotational energy from thecrankshaft 18 to the transmission shaft 20.

When it is desired to reengage the clutch 10, the clutch pedal is letout. This causes the arm 56 to return to the position illustrated inFIG. 1 and restores the spring force of the plate 28 to the pressureplate 26 and hence to the disc 24. At this occurs, the disc 24 is againpressed tightly against the rotating flywheel 12 to produce a turning ofthe transmission shaft 20 with the crankshaft 18.

From the foregoing description of the structure and operation of theclutch assembly 10, it should be apparent that the flywheel 12 plays avery important role in the efficient operation of the clutch. It isimportant that the right radial face of the clutch bearing against thedisc 24 remain smooth and have a high-wear characteristic, if the clutchis to continue to operate efficiently. In addition, it is important thatthe flywheel not warp or become otherwise deformed and produce irregularwearing of the clutch pad. As previously described, it is also veryimportant, particularly in racing cars, that the flywheel be of a lightmass capable of being accelerated and decelerated rapidly.

To accomplish each of the foregoing and to overcome the disadvantage ofprior lightweight flywheels, the present invention contemplates abimetal flywheel construction wherein a central inner portion of theflywheel is formed of a strong metal having high-wear characteristicssurrounded by an outer ring of a lightweight metal. The combinationprovides a flywheel having all of the foregoing desired characteristicswith none of die disadvantages previously encountered in all aluminumflywheels and modifications thereof.

Accordingly, as depicted in FIGS. 2, 3, and 4, the flywheel 12 of thepresent invention includes an inner disc 66 preferably formed of steel,surrounded by an outer ring 68 of a lightweight metal, preferablyaluminum, and secured thereto by interlock means 70. The inner disc 66includes an opening 72 for receiving the end of the crankshaft l8 and issurrounded by a plurality of equally spaced holes 74 for receiving thebolts that secure the flywheel to the crankshaft. A central portion onthe right side of the inner disc 66 is axially relieved at 75 to reducethe weight of the flywheel. The outer radial portion of the right sideis flat and defines the radial surface 76 for engaging the clutch pad,as illustrated in FIG. 1. The left side of the inner disc 66 is alsoaxially relieved by an annular slot 77 to further reduce the weight ofthe flywheel.

As mentioned, the outer ring 68 is formed of a lightweight metal,preferably aluminum. It is secured to the inner disc 66 first by heatingthe outer ring until it expands to an inner diameter slightly largerthan the outer diameter of the disc. The ring is then slipped over theperiphery of the inner disc and allowed to cool and become tightlysecured to the disc. The interlock means 70 further improve the tightconnection between the inner disc and outer ring.

In this regard, the interlock means 70 is adapted to l resist separationof the inner disc 66 and outer ring 68 when pressure is applied throughthe clutch disc 24 against the radial surface 76 of the disc and (2) toresist separation of the inner disc and outer ring when the clutchassembly is disengaged. To accomplish this, the preferred form of theinterlock means 70, illustrated in FIG. 4, includes an annular slot 78in the periphery of the inner disc 66 at the left side thereof defininga step having a vertical shoulder 80. An annular projection 82 extendsradially inward from the inner surface of the outer ring 68 and mateswith the annular slot 78 to nest tightly therein with a verticalshoulder 84 bearing tightly against the vertical shoulder 80. Thusarranged, pressure of the clutch disc 24 against the radial surface 76of the inner disc 66 is opposed by the shoulders bearing against eachother to more tightly secure the inner disc and outer ring togetherthereby resisting separation of the component parts of the flywheelwhile the clutch assembly is engaged.

The interlock means 70 further includes a plurality of screws 86extending axially (parallel to the crankshaft) through the projection 82and into the inner disc 66 through the shoulder 80. The screws 86function to resist separation of the inner disc 66 and outer ring 68when the clutch is disengaged. Under such conditions, a reaction forceto the right is exerted on the inner disc and a reaction force to theleft is exerted on the outer ring. The screws resist such forces andinsure against separation of the component part of the flywheel as theclutch is being disengaged.

You will note from FIG. I that the outer ring 68 is adapted to supportthe inner cover member 22 of the clutch assembly by bolts extendingtherethrough and through the outer radial flange 30. Also, the outerring 68 is adapted to carry a ring gear 88 associated with the starterfor the engine. The balance of the starter is not illustrated butextends into the outer case with a gear mating with the rear gear. Inthis regard, the ring gear 88 nests tightly in an annular slot 90 in theouter surface of the ring 68 and is held in place by the ends of screws92 extending axially into the outer ring as illustrated in FIG. 4.

During operation of a clutch assembly Illustrated In FIG. I,

the inner steel disc 66 resists wear and warpage and maintains a smoothfriction surface 76 for engaging the clutch disc 24 over long periods oftime. The outer ring 68 being aluminum is light weight. Hence the majorportion of the flywheel and that displaced from the crankshaft is of lowmass. This enables the flywheel 12 to be rapidly accelerated anddecelerated. Ac cordingly, the flywheel 12 possesses all the advantagessought for a low-mass flywheel with none of its attendant disadvantages.lclaim: l. A A clutch flywheel comprising: an inner disc of a relativelyheavy, hard metallic material adapted for connection to an end of andfor rotation with an engine crankshaft and defining an inner centralcore for said flywheel, said inner disc having an annular periphery andopposing radial faces comprising inner portions of opposite sides ofsaid flywheel, one of said radial faces having a smooth annular portionfor hearing against a clutch disc;

an outer lightweight metal ring having an inner annular surface aroundsaid annular periphery of said inner disc; and

interlock means on said annular inner surface and said annular peripheryfor locking together said inner disc and said outer ring.

2. The flywheel of claim 1 wherein said interlock means comprise a slotin said periphery of said inner disc and a projection on said outer ringnesting tightly in said slot and said slot and said projection havingmating shoulders for hearing against each other and opposing separationof said inner disc and said outer ring with pressure of said clutch discagainst said annular portion of said radial face,

3. The flywheel of claim 2 wherein said interlock means further includesscrew means extending through said projection into said inner disc.

4. The flywheel of claim I wherein said interlock means comprises anannular slot in said periphery of said inner disc open at a side thereofopposite said one radial face to define a step in said periphery havinga radial shoulder and an axial base and an annular projection from saidinner annular surface of said outer ring tightly engaging said axialbase and in cluding a shoulder mating with said radial shoulder tooppose separation of said outer ring as said clutch disc presses againstsaid annular portion of said radial face.

i l i IF i

1. A A clutch flywheel comprising: an inner disc of a relatively heavy,hard metallic material adapted for connection to an end of and forrotation with an engine crankshaft and defining an inner central corefor said flywheel, said inner disc having an annular periphery andopposing radial faces comprising inner portions of opposite sides ofsaid flywheel, one of said radial faces having a smooth annular portionfor bearing against a clutch disc; an outer lightweight metal ringhaving an inner annular surface around said annular periphery of saidinner disc; and interlock means on said annular inner surface and saidannular periphery for locking together said inner disc and said outerring.
 2. The flywheel of claim 1 wherein said interlock means comprise aslot in said periphery of said inner disc and a projection on said outerring nesting tightly in said slot and said slot and said projectionhaving mating shoulders for bearing against each other and opposingseparation of said inner disc and said outer ring with pressure of saidclutch disc against said annular portion of said radial face.
 3. Theflywheel of claim 2 wherein said interlock means further includes screwmeans extending through said projection into said inner disc.
 4. Theflywheel of claim 1 wherein said interlock means comprises an annularslot in said periphery of said inner disc open at a side thereofopposite said one radial face to define a step in said periphery havinga radial shoulder and an axial base and an annular pRojection from saidinner annular surface of said outer ring tightly engaging said axialbase and including a shoulder mating with said radial shoulder to opposeseparation of said outer ring as said clutch disc presses against saidannular portion of said radial face.